Patent GB-948518-A (GB)
Title: Machine for extruding hollow articles
IPC: B21C23/20
Filed: 1961-11-01
Abstract: 948,518. Extruding. NATIONAL MACHINERY CO. Nov. 1, 1961 [Jan. 30, 1961], No. 39170/61. Heading B3P. [Also in Division B8] A machine for extruding hollow articles along a reciprocable punch has means for transferring blanks, removing extruded articles from the punch, and conveying the articles away, all in timed relationship to the punch movement. The machine is of the horizontal crank operated type with a fixed die 24 and reciprocable punch 28 carried on a slide 13. The punch has a bore 34 for supplying compressed air through a spring-loaded valve 38 in the punch face to aid stripping of the extruded aluminium alloy article 32.  The die holder may be adjusted whilst the machine is operating; referring to Fig. 1, bolts holding a die carrier 21 to a back-plate 18 pass with clearance through a wedge member 19 vertically adjustable by means of a screw 23. As the punch and die heat up the machine will produce articles of progressively greater length and thinner base, thus necessitating moving the die away from the punch. To achieve this, the holding bolts are slackened and the wedge member 19 raised by means of the screw 23. Tension is maintained on the bolts by means of compression springs placed on their shanks, thus providing sufficient clamping pressure between the die holder 21 and wedge member 19 to maintain the axial alignment of the die relative to the punch. Blank transfer, (Fig. 6). Disc shaped blanks 51 are fed down a vertical shoot 52 against a stop 129. A reciprocating carrier 53 transfers blanks 51 to a pair of grippers aligned with-the die aperture 27, the punch forcing the blank from the grippers and into the die aperture. Drive for both transferring and gripping is derived from cams 66, 91 mounted on a shaft 64 driven in timed relationship to the ram crank-shaft. Cam 66 operates a follower 67 and fixed, mutually adjustable rockers 68, 71, pivoted at 74; a link 76 connects the rocker 71 to a slideoperating rocker 77. This link system is loaded by a compression spring 82, which urges the carrier 53 to a position nearest the die. Cam 91 drives a follower 92 carrying a pivoted rod 96 which, by means of a bell-crank lever 94 and push-rod 99, pushes the end 102 of one of the gripping jaws 58 pivoted at 62. Gripping drive to the second gripping jaw 57 is derived directly from jaw 58 through gear sections 63. If a blank is incorrectly held and positioned, gripping jaw 58 will rotate further clockwise than normal which, through a rocker 107, will release a shut-off switch 109, thus stopping the machine. The entire feed frame 61, slider 53 and grippers 57, 58 can be swung clear of the die about a pivot point 111. Article stripping, (Fig. 2). Stripping commences by mechanical engagement of the stripper ring sectors 33 with the outer edge of the article 32 and is later assisted by compressed air blown to the article interior through the valve 38 in the punch. The stripper comprises a series of ring sectors 33 slidably retained between two plates 47, 48, the ring sectors being urged inwardly by a circumscribing coil spring 44. Article conveying, (Fig. 8). After the articles have been stripped, they are carried away between the flights of a conveyer whose intermittent motion is derived from a Geneva mechanism 138, 139 (Fig. 6), which is in turn driven by a chain 132 from a sprocket 133 on the shaft 64. A sensor 164 and associated links co-operate with a stop switch 166 so that if there is no article present when sensing takes place, or if the article is wrongly located in the conveyer, the machine is stopped. Clearly, there is only a short interval in the machine cycle when there should be an article in the sensing position, and the sensor is controlled by a cam 162 mounted on the driving shaft of the Geneva mechanism so as to operate only when an article has just been stripped from the punch. The conveyer unit may be swung clear of the die by rotation about a pivot point 141, by releasing a catch 151; the conveyer is lifted back into its working position by a pneumatic actuator 159.